A laser beam subjected to intensity modulation, such as a pulsed laser beam subjected to intensity modulation, has been increasingly desired as a light source for optical communication, laser material processing, digital video disk, measurement of distance and shape, and the like.
Conventionally, such laser beam subjected to intensity modulation (hereinafter to be referred to as an intensity modulated light) has been obtained by modulating a laser beam continuously output from a laser diode, laser apparatus having a wavelength conversion function and the like, into pulses by various types of intensity modulators set outside the apparatus.
The conventional intensity modulator set outside the apparatus is generally bulky and expensive. Moreover, since an intensity modulator comprising a wavelength conversion crystal (crystal capable of converting the wavelength of light passing through said crystal) and a voltage application means requires application of a modulation voltage creating an intense electric field of approximately .+-.2,000-.+-.20,000 V/cm to said crystal for intensity modulation. The need to apply such a high voltage makes miniaturization of a driving power supply and reduction of necessary electric power difficult to achieve. In addition, various protective means against high voltage application may possibly become necessary.
Accordingly, the present invention aims at solving the above-mentioned problems, and to provide a laser apparatus capable of wavelength conversion of a laser beam oscillated in an optical resonator thereof, and effective intensity modulation of said beam, even by the application of modulation voltage of a level lower than the conventional level, as well as emitting a laser beam which underwent wavelength conversion and intensity modulation, and a method for emitting a laser beam.